# Documentation

Basics: **how home automation works**, **services**, and **CODESYS connectivity**.

## Reference (architecture & setup)

- [Architecture](reference/architecture.md) — Components and data flow
- [Hardware](reference/hardware.md) — Raspberry Pi, EtherCAT, Zigbee
- [Network](reference/network.md) — Topology
- [Setup](reference/setup.md) — Installation order
- [Quick reference](reference/quick-reference.md)

## Services

- [MQTT](integration/mqtt.md) — Broker (LXC)
- [Node-RED](integration/nodered.md) — Automation and CODESYS bridge
- [Home Assistant](integration/homeassistant.md) — Dashboard
- [Zigbee2MQTT](integration/zigbee2mqtt.md) — Zigbee ↔ MQTT

## CODESYS

- [CODESYS configuration](codesys/codesys.md) — Runtime, EtherCAT, NVL
- [PLC algorithm design](codesys/plc-algorithm-design.md) — Logic and I/O
- **NVL (connectivity):** [codesys/src/NVL/README.md](../codesys/src/NVL/README.md) — UDP, NVL_In / NVL_Out, payload layout